The Centre for Environment, Fisheries and Aquaculture Science (Cefas) is an Executive Agency of the Department of Environment, Food and Rural Affairs (Defra), formerly the Ministry of Agriculture, Fisheries and Food (MAFF). It was also known previously as the Directorate of Fisheries Research (DFR). This data policy refers to data collected by the organisation under all titles.

These data have no specific confidentiality restrictions for academic users. However data are restricted for commercial requests and clearance must be obtained by BODC from Cefas before they are released.

Users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgement.

The recommended acknowledgement is: "This study uses data from the Centre for Environment, Fisheries and Aquaculture Science (Cefas), provided by the British Oceanographic Data Centre."

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles have a capacity between 1.7 and 30 L, while Lever Action bottles have a capacity between 1.7 and 12 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

Data Originator

Naomi Greenwood, CEFAS, Lowestoft

Content of data series

Parameter

Units

Parameter code

CTD Samples

Chlorophyll-a concentration

mg m -3

CPHLFLP1

7

Phaeopigment concentration

mg m -3

PHAEFLP1

7

Originator's Protocol

Samples for chlorophyll-a and associated phaeopigments were collected from water bottle rosette sampling systems mounted on the lowered CTD. 7 samples were collected near-surface from a total of 7 CTD stations.

For each sample, a 250ml sample is passed through Whatman GF/F filter under low vacuum. The filter paper is folded in half, loosely wrapped in aluminium foil and placed in plastic bag. Samples are stored in this way in a box containing desiccant at -18° C until analysis. Filters are extracted using 8ml 90% acetone and measured fluorometrically according to Tett (1987) for chlorophyll-a and phaeopigments. CEFAS use a Turner 10AU field fluorometer, which has been calibrated using a pure solution of chlorophyll-a.

BODC Processing

The data were supplied to BODC as an Excel spreadsheet. This was converted to an ASCII format file for loading into the BODC archive. Methodology and units were checked against information held in the BODC parameter dictionary and an appropriate parameter code was attributed to each variable. The file's data and metadata fields were then checked prior to loading into a database.

The data were loaded into the database under the Oracle Relational Database Management System by matching the sample's station identifier and depth with the information already held in the database for this cruise. Where the data supplied included multiple replicates for each station, the mean value and standard deviation were loaded into the database. For single samples, the data were loaded without further modification.

Comments on data quality and outstanding issues

There are no outstanding issues regarding this dataset.

References

Conditions of Use

CEFAS Disclaimer: "Reproduction of this material is limited to academic and educational uses only and not for any commercial purposes without permission from CEFAS. The data are provided "as is" and in no event shall CEFAS be liable for any damages, including, without limitation, any disruption, damage and/or loss to your data or computer system that may occur while using this site or data. CEFAS makes no warranty, express or implied, including the warranties of merchantability and fitness for a particular purpose; nor assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any data, information, apparatus, product, or process disclosed; nor represents that its use would not infringe the rights of any third party."

The Data Originator must be informed that the supply has occurred.

Due acknowledgement of the Originator and the Originator's Institute is made by the receiver in any product using the data.

Proudman Oceanographic Laboratory Coastal Observatory

The Coastal Observatory was established by Proudman Oceanographic Laboratory as a coastal zone real time observing and monitoring system. The main objective is to understand a coastal sea's response both to natural forcing and to the consequences of human activity. Near real-time measurements will be integrated with coupled models into a pre-operational coastal prediction system whose results will be displayed on the World Wide Web.

The Observatory is expected to grow and evolve as resources and technology allow, all the while building up long time series. A site selection pilot study was carried out in September 2001 and the Observatory became operational in August 2002.

The site is located in Liverpool Bay and is subject to typical coastal sea processes, with strong tides, occasional large storm surges and waves, freshwater input, stable and unstable stratification, high suspended sediment concentration and biogeochemical interaction. Measurements and monitoring will focus on the impacts of storms, variations in river discharge (especially the Mersey), seasonality and blooms in Liverpool Bay.

A variety of methods will be used to obtain measurements, including:

Moored instruments for in situ time series of currents, temperature and salinity profiles, and surface waves and meteorology. It is hoped that turbidity and chlorophyll measurements will be made at another site as the Observatory progresses;

The Cefas Smartbuoy for surface properties such as nutrients and chlorophyll, starting late 2002;

R.V. Prince Madog to carry out spatial surveys and service moorings;

Instrumented ferries for near surface temperature, salinity, turbidity, chlorophyll and nutrients. The first route will be Liverpool to Douglas, Isle of Man, starting late 2002;

Drifters for surface currents and properties such as temperature and salinity, starting in 2004;

Tide gauges, with sensors for meteorology, waves, temperature and salinity, where appropriate;

Please note:the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.